1. Field of the Invention
The present invention generally relates to an aircraft, missile, projectile, or underwater vehicle with an improved control system, and to an improved control system by itself for maneuvering these aircraft, missile, projectile or underwater vehicle. More particularly, the present invention relates to removable, and variable control surfaces for adaptively modifying the aircraft missile, projectile or underwater vehicle's stability which also affects the maneuvering performance, in-flight.
2. Technical Background
The ability to adaptively modify and control a vehicle's static and dynamic stability in-flight has vast potential in diverse aeronautical and underwater applications including extreme vehicle maneuvering, collision avoidance, collision seeking, end-game maneuvering, stall prevention, and managing aerodynamic forces and moments. There is no doubt, that in the era of growing aeronautical and aerospace use, air vehicles with fast-acting control surfaces and methodologies that allow dynamic, in-flight reconfiguration of the vehicle's stability and aerodynamic performance are critical to the success and development of the next-generation, high-performance vehicles. Examples include weapons that are designed to seek-and-destroy moving and emerging high-priority targets, active flares that are deployed from aircraft to defend against enemy missiles, or fighter aircraft that need rapid maneuvering capabilities during dog-fighting. In general, it is highly desirable to have an aircraft, missile, projectile, or underwater vehicle be able to readjust its path in a quick and effective manner. In the case of missiles or projectiles, it is not only desirable but necessary to possess the ability to actively adjust the vehicle stability and maneuverability in-flight so as to sustain high loads during launch and to pursue moving targets, respectively.
Stability and maneuverability are functions of the relative positions of center of gravity and center of pressure. The center of pressure is determined by the relative placement of the surface area. As the fluid flows over the surface it, exerts a pressure upon that surface. By integrating the total pressure around the vehicle, the net force and moment is determined, which defines the vehicle's stability. With more pressure towards the rear of the vehicle, the center of pressure moves towards the rear, and vice versa. The vehicle's center of gravity is based upon the weight distribution, in that more weight towards the front or the back of the vehicle will correspondingly alter the center of gravity towards the front or the back, respectively. The further the center of pressure is located aft of the center of gravity, it provides greater stability to the vehicle. Alternatively, reducing the distance between the center of mass and the center of pressure leads to a less stable, and hence, a more maneuverable vehicle. Consequently, to create a more stable vehicle, control surfaces are typically placed near the rear, behind the center of gravity. This increase in stability however has the drawback of leading to a less maneuverable configuration.
The trade-off between stability and maneuverability is always a challenging assessment in the case of vehicles that require both ‘stable flight’ and ‘supermaneuverability’ during different stages of their flight envelope. An example of such a vehicle is a small rocket-powered flare or a projectile that is used as a defensive countermeasure for aircraft against enemy missiles. For a successful employment of such a countermeasure system, the flare needs to be fired from an aircraft in such a way that it can be maneuvered into the path of the incoming missile for physical interception and destruction. This style of execution requires both heightened stability and supermaneuverability, which is uncharacteristic of traditional flares or air vehicles.
Additional problems with control surface designs arise when a missile or projectile must be fired at an angle from a fast moving aircraft. A missile or projectile fired at an angle from a quickly moving aircraft must be extremely stable to overcome the high cross-winds and yawing moment during the launch phase. Inadequate stability will result in the missile or projectile tumbling out of control shortly after launch. Air-to-air and air-to-ground missiles are normally fired in the same direction the aircraft that launched it is flying. Any change in direction away from that of the aircraft from which it was fired, occurs after the missile or projectile is in flight. This eliminates any cross winds caused by the forward motion of the aircraft as the winds will be parallel with the bodies of the aircraft and missile or projectile. However, when an air-to-air or air-to-ground missile is fired at any angle not directly forward or directly backwards of the aircraft (0 and 180 degrees respectively), they are subject to crosswinds generated by the forward movement of the aircraft. The higher the launch angle is away from 0 or 180 degrees, the greater the crosswinds. The crosswinds will increase approaching 90 degrees from forward where they will be greatest, and decrease approaching 180 degrees where they will return to 0. Overcoming the cross-winds and yawing moment requires large control surfaces for stability. But a missile or projectile with large control surfaces will not be able to adequately maneuver because its large control surfaces place its center of pressure far behind its center of mass. This problem has thus far prevented large scale use of aircraft-launched missiles or projectiles that are launched at an angle.
Creating vehicles with high stability and maneuverability has long been a goal in the art, and has been accomplished by a number of means. Canards, elevators, ailerons, elevons and other forms of control surfaces are typically used to provide control and stability. However, most vehicles have a single-point design, where the design of the aerodynamic control system is optimized for the conditions likely to be encountered for the majority of the vehicle's flight path. To design vehicles that are both stable as well as maneuverable, multi-point designs involving adaptive, in-flight modifications to the control surfaces are proposed.
In view of the foregoing inherent disadvantages with presently available aircraft, missile, projectile, and underwater vehicle control devices, it is an object of the present invention to develop a system and a methodology for allowing these vehicles to transition from one configuration to another configuration using removable control surfaces.
It is a further object of this invention to provide a molting control surface of the character described wherein the molting pieces are detached in-flight to modify the aircraft, missile, projectile or underwater vehicle's stability, drag, or its ability to turn in the pitch, yaw, and roll axes.